Location of air/fuel mixture screw on Yamaha xt 125 r

I have cleaned my carb but now the problem is it will only start when the choke is on and when I turn it off the bike cuts out so I'm thinking its the air/fuel mixture but I don't know which screw it is I know which one is the idle

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There have an air leak between the carb and the cylinder and/or the head and cylinder. Old hard / cracked rubber fittings and O rings are usually the problem. When extra air gets into the system it leans the fuel mix and the high idle is the result. It also means the engine runs hotter. Also, cracked or broken reeds can be a source.

Hi, You have a closed mainjet (need cleaning) as for idling you must screw in all the way and then unscrew 2 turns (that's a standart) and then you only have to do minor adjustments.
As for the needle position they all work the highest grove you set the more fuel to your engine. Start from the lowest, test the bike for power and rpm's and adjust from there
Good luck

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No, nothing else to check. You need to completely disassemble the carb and clean it out. When gasoline left in the float bowl evaporated, it left behind the gummy additives that the refinery puts in the gasoline. This mess has clogged the jets and small passageways in the carb. The reason it runs with the "choke" out is that it is not a real "choke" but rather an "enricher circuit". It has it's own air passageway and fuel metering "jet" in the float bowl.

You are correct about carb dissembling & cleaning bare min drop bowels & carb clean the jets idle & main any adj screws remove & spray out passages. count the turns so to replace screws to same place.. biker bandit may have some dias...

well you hit it right on the head there,, its the jets in the carb blocked up,,strip down carb and clean out all the jets with carb cleaner and compressed air dont go poking any thing into the jets as you will distroy them that way,,, another way of clearing the jets out that you could try first is,,,take off the air filter and start the engine up on choke in needs be,,rev the motor up high and slam your hand over the carb intake,,removing it just before the motor cuts out do this a good fuw times and it some times??? only some times clears the carb jets out for you

sounds like the carbs need cleaning...if its been stood for a while..petrol thats in the carbs goes off....so you will need to take the carbs of the bike & take the float bowls off to clean them out...& do the jets as well...has these have small holes in them .petrol goes threw these & gum up....thats why your bike wont rev!!..its not getting enuf petrol!!...hope this helps

Adjust your idle screw on your carb so that it gets more gas just sitting there at idle. Tighten the screw one and a quarter turn and then start the bike. Adjust the idle to where you think it sounds normal. If that doesnt work check your float in your float bowl, it might be stuck in the down position. Clean with some carb cleaner spray and make sure it moves freely before putting the float bowl back on, youll have to choke it or prime the carb again to get it started. All the choke does is let in more gas and oxegen so you might want to check how far the carbs close when you push the choke back in. Is it impeading any normal carb setting. Check that too. Good luck.

I am having a similiar problem. bmw r 1100 s will only start with full choke and will die if I cut off choke or give it any throttle. This is my first bike and it has been sitting in a garage for 2 years. I took out the carbs, cleaned them and rebuilt them. I didn't find any residual in the carbs and they were very clean. Today, I was able to get the bike running and took it down the neighborhood but after the bike warms up it idles at 6K! Man... If I can't find any answers from this forum, I will probably drop it off at the motorcycle shop just down the hill from me. Any suggestions anyone? I think I will try to drain the fuel and give it new gas. But still....